A model system for the study of genital infection by Chlamydia will be investigated using guinea pigs and the agent of guinea pig inclusion conjunctivitis (Gp-ic). Male guinea pigs will be inoculated intraurethrally and the clinical response determined with particular reference to the development of lesions on the penis and legs. The course of infection will be followed by examination of smears, histopathology (light and electron microscopy), isolation Gp-ic, detection of Gp-ic antigen by immunofluorescence and immunoperoxidase, cellular immune response, and determination of antibodies. Resistance to reinfection in the genital tract will be evaluated in male and female guinea pigs. The presence of antibodies in genital secretions of females will be examined and the role of secretory IgA in recovery and resistance investigated. The effect of infection on stillbirths and offspring will be studied. Intrarectal route of inoculation will be attempted in extending the use of the model. Experiments will be conducted to learn the value of this model for the study of genital infection by chlamydial strains isolated from cases of lymphogranuloma venereum.